This invention relates generally to rotary die cylinders used in the printing industry and particularly to a rotary die cylinder assembly having an improved means of attaching rotary cutting tools and the like used for slitting, scoring, perforating or line hole punching operations, to the cylinder.
The conventional method of attaching rotary knives, dies and bearers and the like onto cylinders is by the use of square or rectangular keys, disposed between the cylinder and the member to be attached, in combination with a set-screw provided in the attached member and engaging a flat or conical groove provided on the cylinder. The key is intended to prevent relative rotational movement and the set screw to prevent relative longitudinal movement of the attached member. The disadvantage of this system of attachment lies in the inherent mismatch potential of standard keys and keyways and to the tendency of individual set screws to permit cocking of the mounted member within the clearance range of the connected parts.
Although there have been improvements proposed to overcome these disadvantages, such proposals take a different approach to that proposed in the present invention. For example, U.S. Pat. No. 2,807,485 (Seibert) discloses a tubular slotted key that is expanded by the set screw of the mounted member. U.S. Pat. No. 780,850 (Williams) discloses a set screw used in combination with multiple pressure bars to hold the mounted member in place. U.S. Pat. No. 3,951,024 (Weiskopf) discloses the use of fluid pressure applied throught the shaft to hold pressure hoses against a rectangular key. The special devices inherently utilize complicated and therefore inevitably expensive parts.
The present invention avoids the above disadvantages in a manner not revealed by the known prior art.